Just a few notes:
1. Struts doesn't dissallow the operations you outline below. If you are
using Struts, and you really need to do this, you can make the same calls
from your Action implementation.
public class SomeAction extends Action {
public ActionForward perform(ActionMapping mapping, ActionForm form,
HttpServletRequest request, HttpServletResponse response)
throws IOException, ServletException {
ServletContext context = servlet.getServletContext();
RequestDispatcher dispatcher = context.getRequestDispatcher(<jspFile>);
rs <- <dbquery>
request.setAttribute("rs", rs);
dispatcher.include(request, response);
rs.close();
// ActionServlet doesn't do any more response processing..
return null;
}
}
I'm not suggesting that coding this way is wrong. I would suggest that this
isn't optimal model/view separation, which is one of the main motives for
using Struts, right?
2. My use of the term "acquiring" may have been wrong, or at least
ambiguous. More accurately, I would suggest that view components should not
have knowledge of, or responsibility for non-memory, finite resources.
3. You must rely on Garbage collection in Java, you may not like its
behaviors, but its all you get. Also, I would never suggest that you rely on
garbage collection to free, non-memory resources, like db-handles.
-- Levi
-----Original Message-----
From: Jeff Trent [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, June 05, 2001 2:05 PM
To: [EMAIL PROTECTED]
Subject: Re: Managing resource life cycle during request
Levi,
The view/JSP does not acquire the resource. Here is a sample of how the
code use to work pre-struts:
Servlet.doGet()
{
...
rs <- <dbquery>
request.setAttribute("rs", rs)
requestDispatcher.include(<jspFile>)
rs.close();
}
In JSP:
...
rs = request.getAttribute("rs")
while (rs.next())
{
...
}
- - -
The problem is that there is no appropriate counterpart in the world of
struts. Sure, I can copy the row data to a collection and then walk the
collection. But for various reasons, this may be inappropriate (especially
for large result sets represented by a cursor).
Finally, you should not depend on garbage collection. The garbage collector
is not always called and its certainly not called as often as you would want
it to when you need to free scarce resources like db handles.
- jeff
----- Original Message -----
From: "Cook, Levi" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Tuesday, June 05, 2001 1:40 PM
Subject: RE: Managing resource life cycle during request
> Can you elaborate on your resource cleanup requirements?
>
> My view on designing a responsible object is that I must make sure it
> eventually releases any, non-memory, finite resources it uses. This design
> strategy, coupled with garbage collection ensures my system doesn't run
out
> of those resources (eg. file handles, sockets, etc.).
>
> Given that ActionForms and JSPs should play the "view" role in Struts, I
> would question a design that has them acquiring non-memory resources. But,
> alas, I don't know your system or situation..
>
> Regards,
> Levi Cook
>
>
> -----Original Message-----
> From: Ted Husted [mailto:[EMAIL PROTECTED]]
> Sent: Monday, June 04, 2001 10:31 PM
> To: [EMAIL PROTECTED]
> Subject: Re: Managing resource life cycle during request
>
>
> I doubt that overriding ActionServlet.process() would work. The
> controller sends back the response, and it's done. It's then up to HTTP
> to deliver the view, usually a JSP.
>
> Any clean-up routine would have to be the responsibility of the view,
> which puts you into the scriplet zone.
>
> Jeff Trent wrote:
> >
> > Well, it looks to me that short of overriding ActionServlet.process(),
> there
> > is no way one can clean-up resources after the page has been rendered...
>
